Rodding jet

ABSTRACT

A method and apparatus for rodding conduits in which the projectile is self-propelling by rearwardly directed gas ejection means and propellant gas is fed under pressure to the projectile from a source through a line of flexible tubing attached to the projectile.

United States Patent John E. Bowden Stratford, Ontario;

Murray R. McLarty, J r., Peterborough, Ontario; Robert V. Zeller, Mississauga, Ontario, Canada Feb. 20, 1969 Jan. 12, 1971 Bell Canada Montreal, Quebec, Canada Inventors Appl. No. Filed Patented Assignee RODDING JET 10 Claims, 2 Drawing Figs.

US. Cl .7 254/134-3 lnt.Cl E2lc 29/16 Field ofSearch 254/134.3,

134.4; 243/(lnquired); 302/2 [56] References Cited UNITED STATES PATENTS 2,930,584 3/1960 Hensley 254/ 1 34.3 3,120,947 2/ 1964 Hamrick 254/1 34.4

Primary Examiner-Andrew R. Juhasz Assistant Examiner-David R. Melton Attorney-Waste and l-lanley ABSTRACT: A method and apparatus for rodding conduits in which the projectile is self-propelling by rearwardly directed gas ejection means and propellant gas is fed under pressure to the projectile from a source through a line of flexible tubing attached to the projectile.

PATENIEU JAN 1 2197:

INVENTORS JOHN E. BCW DEN MURRAY R. McLARTY ROBERT J. ZELLER BYWMM RODDING JET The present invention relates to a method and apparatus for rodding conduits.

The usual method of passing a telephone cable through an underground conduit employs a pneumatic rodder which comprises a projectile having a line attached to it, the projectile being propelled by compressed air using the conduit as a barrel. As the projectile traverses the conduit it unwinds the line from a reel located adjacent the starting" end of the conduit. An example of this type of rodder is shown in US. Pat. No. 423,134 issued Mar. 11, 1890 to T. A. Cope. A disadvantage of this known device is that the projectile must have a diameter substantially equal to that of the conduit in order that the compressed air will not be dissipated, with the result that any obstacle in the conduit, such as cables already present, will block the passage of the projectile through it. A second disadvantage of this type of rodder is that it cannot be used in Y connections because the effectiveness of the conduit as a barrel is destroyed once the projectile passes the connection point. To overcome these disadvantages a modification of the standard type of rodder has been developed, as shown in Canadian Pat. No. 666,376 issued July 9, 1963 in the name of O. l... Hensley et. al., in which a gas bottle is used as the projectile and supplies its own pellet. A disadvantage of this modified device is that the projectile may be stopped by an obstacle and expend its propellent, making it necessary to retrieve the spent projectile and repeat the operation.

These disadvantages are overcome by the present invention in which a conduit is rodded by a projectile which is selfpropelling with propellant being supplied to it from an external source.

In its broadest apect the invention resides in a method of rodding a conduit, comprising the steps of: attaching a line of flexible tubing to a projectile having rearwardly directed gas ejection means; positioning the projectile adjacent one end of the conduit; and feeding gas under pressure through the tubing to the gas ejection means whereby the projectile is propelled through the conduit with the tubing attached thereto.

In another aspect the invention resides in a projectile for use in rodding a conduit, comprising: a body; means to attach a line of flexible tubing'to the body; gas ejection means opening rearwardly from the body; and passage means in the body interconnecting the tubing with the gas ejection means. The invention also consists of an apparatus for rodding a conduit including the aforementioned projectile and means for delivering gas under presure through the tubing to the projectile whereby ejection of the gas propels the projectile through the conduit.

An example embodiment of the invention is shown in the accompanying drawings in which:

FIG. 1 is a view in perspective of the rodding device, showing the projectile traversing a conduit; and

FIG. 2 is a view in longitudinal cross section of the device shown in FIG. 1, taken along line 2-2.

The illustrated embodiment of the invention consists of a projectile having a body comprising a cylindrical main portion 11, a front nose cone 12, and a conical throttling valve 13. A cylindrical chamber 14 in main body portion 11 opens rearwardly to form an annular wall terminating in a circular rim l6. Throttling valve 13 is mounted concentrically within chamber 14 and projects rearwardly through the open end of the chamber to form, with rim 16, an annular orifice 17. A threaded shaft 19 projects axially from apex 20 of valve 13 and engages coaxial threaded bores 21 and 22 axially located in body portion 11 and nose cone 12 respectively. A threaded boss 23 extends axially from the base of valve 13. A passage 24 extends from apex 20 of valve 13 axially through the valve and through boss 23, opening rearwardly through an annular spigot 25 extending from the boss. A plurality of ports 26 open laterally from passage 24 through apex 20 of yalve 13.

In the assembly of projectile l0, shaft 19 is threaded through bores 21 and 22 to interlock nose cone 12 with main body portion 11. The axial position of valve 13 in chamber 14,

and thus the size of annular orifice 17, is preferably predetermined by constructing the projectile to have shaft 19 extend to the end of passage 22 thereby locking the shaft with the nose cone.

To form the rodder unit a flexible hose or tube 27 is attached to valve 13 by means of a nut 28 which is mounted on a nylon gasket 29 press-fitted onto the end of hose 27. Nut 28 is rotatable on gasket 29 and engageable with threaded boss 23 on valve 13, when the end of hose 27 is slipped over spigot 25, to lock the hose onto projectile 10.

In the operation of the rodder unit, projectile 10, with hose 27 attached to it, is placed at the entrance to a conduit 30 through which a line is to be passed. Hose 27, having a length at least as great as the length of conduit 30, is coiled adjacent the conduit with its other end connected with a source of pressurized gas (not shown) which may for example be air or nitrogen. The pressurized gas is passed through hose 27, in the direction of arrow 31 in the drawings and along passage 23 of valve 13, passing out through ports 26 into chamber 14 as indicated by arrows 32 and thence ejected through annular orifice 17 of projectile 10 as indicated by arrows 33. The thrust of the pressurized gas through orifice l7 propels the projectile forward through conduit 30 in the direction of arrow 34, dragging hose 27 behind it. The speed of projectile 10 through conduit 30 may be controlled either by adjusting the pressure of the gas fed into it through hose 27 or by altering the size of orifice 17 by changing the axial location of valve 13 within chamber 14 of body portion 11. If projectile 10 becomes blocked within conduit 30, it can be retracted slightly by pulling on hose 27 and then allowed to move forward again; in this manner the projectile will find its way around the obstacle provided that the space is large enough to allow it to pass freely.

Hose or tube 27 must be made of a material which is flexible, will coil and uncoil when filled with pressurized gas, and will accommodate a gas pressure sufficiently high to propel projectile 10 without bursting. Polyethylene tubing having an outer diameter of one-half inch and a wall diameter of one-sixteenth inch has been found suitable for the purpose, having a bursting pressure of 70 pounds per square inch. Using this hose and the embodiment shown in the drawings, successful rodding of conduits up to 500 feet in length has been accomplished; this is usually the maximum distance between main conduit runs between man holes in urban areas. In these runs a cylinder of nitrogen having a maximum pressure of 2,500 pounds per square inch was used, the flow from the cylinder to tube 27 being controlled by an adjustable valve.

Of course, to simplify the construction of the rodding unit. projectile 10 could consist of a solid body having passages therein leading from tubing 27 and opening rearwardly in a plurality of orifices circumscribing the tubing in an annular array where the tubing is attached to the projectile.

We claim:

l. A method of rodding aconduit, comprising the steps of:

attaching a line of flexible tubing to a projectile having rearwardly directed gas ejection means;

positioning the projectile adjacent one end of the conduit;

and feeding gas under pressure through the tubing to the gas ejection means whereby the projectile is propelled through the conduit with the tubing attached thereto.

2. A projectile for use in rodding a conduit, comprising:

a body;

means to attach a line of flexible tubing to the body;

gas ejection means opening rearwardly from the body; and

passage means in the body interconnecting the tubing with the gas ejection means.

3. A projectile as defined in claim 2 in which the passage means includes a chamber opening rearwardly thereof, and a conical valve mounted in the chamber to define, with the opening of the chamber, a peripheral orifice comprising the gas ejection means.

4. A projectile as defined in claim 3 in which the valve is adjustable axially with respect to the opening of the chamber to vary the size of the orifice.

5. A projectile as defined in claim 3 in which the tube attachment means is mounted on the base of the conical valve, the valve having a passageway interconnecting the attachment means with the chamber.

6. A projectile as defined in claim 2 in which the passage means includes a chamber opening rearwardly thereof and conical valve mounted in the chamber to define, with the opening of the chamber, a peripheral orifice comprising the gas ejection means; the tube attachment means being mounted on the base of the valve; the valve having a passageway interconnecting the tube attachment means and the chamber; and a shaft projecting coaxially from the apex of the valve and threaded into the body whereby the valve is adjustable axially with the opening of the chamber to vary the size of the orifice. i

7. A projectile as defined in claim 2 in which the passage means comprises a plurality of passages leading from the tubing attachment means, the plurality of passages circumscribing said means in an annular array and opening rearwardly from the body to form the gas ejection. means.

8. Apparatus for rodding a conduit, comprising:

a projectile having gas ejection means at its rearward end;

a line of flexible tubing leading from the rearward end of the projectile; passage means within the projectile interconnecting the tubing and the gas ejection means; and means for delivering gas under pressure through the tubing to the projectile whereby ejection of the gas propels the projectile through the'conduit. I 9. Apparatus as defined in claim -7 in which the projectile comprises a cylindrical body having a chamber opening rearwardly thereof, a valve seated in'the opening of the chamber to form therewith an annular orifice defining the gas ejection means, the flexible tubing being attached-to the valve and interconnecting with the chamber by a passage through the valve, the valve being connected to the main body portion at the base of the chamber and adjustable axially therewith 10. Apparatus as defined in claim 7 in which the passage means comprises a plurality of passages leading from the tubing, the plurality of passages circumscribing the tubing in an annular array and opening rearwardly from the body to form.

the gas ejection means.

. UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,554, 493 Dated January 12;,- 1971 Invent0r($) John E. Bowden, Murray R McLarty and Robert J. Ze11 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the claims, column 4, lines 8 and 16, for the claim reference numeral "7", each occurrence, should read 8 Signed and sealed this 7th day of September 1971.

(SEAL) Attest:

EDWARD MELETCHER, ROBERT GOTTSCHALK Attesting Officer Actlng Commissioner of Patent 

1. A method of rodding a conduit, comprising the steps of: attaching a line of flexible tubing to a projectile having rearwardly directed gas ejection means; positioning the projectile adjacent one end of the conduit; and feeding gas under pressure through the tubing to the gas ejection means whereby the projectile is propelled through the conduit with the tubing attached thereto.
 2. A projectile for use in rodding a conduit, comprising: a body; means to attach a line of flexible tubing to the body; gas ejection means opening rearwardly from the body; and passage means in the body interconnecting the tubing with the gas ejection means.
 3. A projectile as defined in claim 2 in which the passage means includes a chamber opening rearwardly thereof, and a conical valve mounted in the chamber to define, with the opening of the chamber, a peripheral orifice comprising the gas ejection means.
 4. A projectile as defined in claim 3 in which the valve is adjustable axially with respect to the opening of the chamber to vary the size of the orifice.
 5. A projectile as defined in claim 3 in which the tube attachment means is mounted on the base of the conical valve, the valve having a passageway interconnecting the attachment means with the chamber.
 6. A projectile as defined in claim 2 in which the passage means includes a chamber opening rearwardly thereof and conical valve mounted in the chamber to define, with the opening of the chamber, a peripheral orifice comprising the gas ejection means; the tube attachment means being mounted on the base of the valve; the valve having a passageway interconnecting the tube attachment means and the chamber; and a shaft projecting coaxially from the apex of the valve and threaded into the body whereby the valve is adjustable axially with the opening of the chamber to vary the size of the orifice.
 7. A projectile as defined in claim 2 in which the passage means comprises a plurality of passages leading from the tubing attachment means, the plurality of passages circumscribing said means in an annular array and opening rearwardly from the body to form the gas ejection means.
 8. Apparatus for rodding a conduit, comprising: a projectile having gas ejection means at its rearward end; a line of flexible tubing leading from the rearward end of the projectile; passage means within the projectile interconnecting the tubing and the gas ejection means; and means for delivering gas under pressure through the tubing to the projectile whereby ejection of the gas propels the projectile through the conduit.
 9. Apparatus as defined in claim 7 in which the projectile comprises a cylindrical body having a chamber opening rearwardly thereof, a valve seated in the opening of the chamber to form therewith an annular orifice defining the gas ejection means, the flexible tubing being attached to the valve and interconnecting with the chamber by a passage through the valve, the valve being connected to the main body portion at the base of the chamber and adjustable axially therewith.
 10. Apparatus as defined in claim 7 in which the passage means comprises a plurality of passages leading from the tubing, the plurality of passages circumscribing the tubing in an annular array and opening rearwardly from the body to form the gas ejection means. 